In addition to SCLC, other CD56+ cancers include multiple myeloma and Merkel cell carcinoma. In early-stage clinical testing, IMGN901 has demonstrated encouraging activity in these cancers as well as in SCLC and also has orphan drug designation for them.About SCLC It is estimated that approximately 29,400 new cases of SCLC will be diagnosed in the United States this year. 1 SCLC almost universally expresses CD56. Approximately two-thirds of patients have extensive disease at the time of diagnosis, as SCLC tends to spread broadly through the body quite early in its course. 2 As a result, SCLC is usually treated with chemotherapy rather than with surgery. 3 Median PFS for extensive disease SCLC is approximately 5.5 months, while median overall survival averages 9-11 months. 3,4 About ImmunoGen, Inc. ImmunoGen, Inc. develops targeted anticancer therapeutics using the Company's expertise in tumor biology, monoclonal antibodies, potent cancer-cell killing agents and engineered linkers. The Company's TAP technology uses monoclonal antibodies to deliver one of ImmunoGen's proprietary cancer-killing agents specifically to tumor cells. There are now ten TAP compounds in clinical development, of which three are wholly owned by the Company. ImmunoGen’s collaborative partners include Amgen, Bayer HealthCare, Biotest, Lilly, Novartis, Roche, and Sanofi. A marketing application for trastuzumab emtansine (T-DM1), the most advanced compound using ImmunoGen's TAP technology, has been submitted in the US. Roche is developing this compound under an agreement between ImmunoGen and Genentech, a member of the Roche Group. More information about ImmunoGen can be found at www.immunogen.com. ¹ American Cancer Society, Cancer Facts & Figures 2012. 2 American Cancer Society, Lung Cancer (Small Cell) 2012. 3Socinski, MA, Smith, EF, Lorigan, P, et al. (2009). J Clin Oncol, 27(28). 4Foster, NR, Qi, Y, Krook, JE, et al. (2009). J Clin Oncol, 27(15s). This press release includes forward-looking statements. For these statements, ImmunoGen claims the protection of the safe harbor for forward-looking statements provided by the Private Securities Litigation Reform Act of 1995. It should be noted that there are risks and uncertainties related to the development of novel anticancer products, including IMGN901, including risks related to clinical studies, their timings and results. A review of these risks can be found in ImmunoGen’s Annual Report on Form 10-K for the fiscal year ended June 30, 2012 and other reports filed with the Securities and Exchange Commission.